Display screen or portion thereof with a graphical user interface



FIG. 1 is a front view of a first image in a sequence for a display screen or portion thereof with a graphical user interface;

FIG. 2 is a front view of a second image thereof;

FIG. 3 is a front view of a third image thereof;

FIG. 4 is a front view of a fourth image thereof;

FIG. 5 is a front view of a fifth image thereof;

FIG. 6 is a front view of a sixth image thereof;

FIG. 7 is a front view of a seventh image thereof;

FIG. 8 is a front view of an eighth image thereof; and,

FIG. 9 is a front view of a ninth image thereof.

The appearance of the images sequentially transitions through FIGS. 1-9. The process or period through which one image transitions to another forms no part of the claimed design. The broken lines illustrate portions of the graphical user interface that form no part of the claimed design. The outer edge of the portion of the display screen is understood to be congruent with the outer edge of the graphical user interface. 

CLAIM The ornamental design for the display screen or portion thereof with a graphical user interface, as shown and described. 